The present invention relates to trip computers for vehicles and more particularly to a trip computer which is capable of computing a capable travel distance suitably even just after having connected the trip computer to the vehicle battery by turning on the key switch suitably.
Apparatus heretofore known as automobile trip computers or drive computers have a function of computing a capable travel distance as a predicted information and it is derived by the following calculation. ##EQU1##
However, there is a disadvantage that if this data is not satisfactorily accurate, the computation of a capable travel distance results in a value which differs considerably from the correct value. It has been the usual practice to compute the gas mileage in the following manner due to the inability to directly input the data which is necessary for computation: ##EQU2## However, where the totalized data, e.g., the traveled distance and the consumed fuel amount are small, the effect of this totalized or integrated data is lost so that due to the running conditions, etc., there is the danger of the resulting gas mileage value being varied suddenly and impeding the computation of a capable travel distance. Usually, the traveled distance and the consumed fuel amount are stored as data in the RAM of a microcomputer so that even if the key switch is turned off, at least because of the data holding function there is no danger of the various data being cleared or destroyed. However, problems will be caused if the microcomputer in the deenergized condition is again connected to the power source. For instance, if the automobile is garaged or when the battery is removed, there is a disadvantage that at the instant the microcomputer is again connected to the battery, the microcomputer will be reset thus clearing the data (the traveled distance and the consumed fuel amount) in the RAM altogether and that until the time that the necessary parameters are increased satisfactorily after the start of the automobile the computed gas mileage value will be caused to vary considerably thus failing to ensure the desired computation accuracy of the capable travel distance.